NEW YORK — AT&T suspended online sales of iPhones to New Yorkers over the weekend for unknown reasons, then abruptly started selling them again just as mysteriously Monday.

Spokesman Fletcher Cook said only that the phone company periodically “modifies” its distribution channels. He had no further comment on the resumption in sales, and officials with phone maker Apple did not immediately return messages for comment.

Bloggers speculated that the sales suspension was a means of managing data traffic, since AT&T has acknowledged that its network is overburdened with iPhone users in New York and San Francisco.

However, because the phones were still available in New York retail stores and from Apple’s Web site, the ban may have instead been an attempt to curb buyers who renege on the service contracts and resell the phones to customers of other carriers overseas.

On AT&T’s Web site, buyers who supplied New York City ZIP codes were told Monday morning to “Please shop for another phone.”

By afternoon, though, the Web site raised no obstacles when the same ZIP codes were supplied.

It was not clear whether the iPhone suspension had applied to all New York ZIP codes or just certain ones, nor was it known why New York was targeted.

"There is a general recognition that we don't need these military-style weapons in New Zealand, so it's very easy to win cross-party support for this," said Mark Mitchell, who was defense minister in the previous, center-right government and who supports the ban initiated by the center-left-led Labour Party.